The x% rule is to withdraw x% of your portfolio in the first year and adjust your withdrawals for inflation in later years. The lower the x, the lower your chance of running out of money, but also the less you get to you enjoy spending from your life savings. Any x% rule is very flawed, since it ignore investment returns. Better is a Variable Percentage Withdrawal rule https://www.bogleheads.org/wiki/Variable_percentage_withdraw..., that does not.